Hot-air furnace.



No. 676,784. Patented lune I8, I90l. R. S. THOMPSON.

HOT AIB FUBNACE.

(Application led Mar. 20, 1901.7 (No Model.) 2 Sheets-Sheet l.

HUTU AIR FURNACE.

(Application led Mar. 20, 1901.)

y2 Sheets-Sheet 2.

(llo lodel.)

fria/pff.

fue Dams Perlas co. morauwo.. wAsHmsoN. D. c.

Nrrnn Sterns Minst trice,

RALPH S. THOMPSON, OF SPRINGFIELD, OHIO.

HOT-AIR FU RNACE.

SPEGIFICATION forming part of Letters Patent No. 676,784, dated J' une 18, 1901. Application tiled March 20, 1901. Serial No. 52,066. (No model.)

T all whom t may concern,.-

Be it known that I, RALPH S. THOMPSON, a citizen ofthe United States, residingatSpringfield, in the county of Clark and State of Ohio, have invented certain new and useful Improvements in Hot-Air Furnaces, of which the following is a specification, reference being had therein to the accompanying drawings. l

This invention relates to hot-air furnaces, and in the particular form shown in the accompanying drawings is more particularly designed for use in connection with fuel-gas,

the general principles of construction involved being, however, equally applicable to other fuels, such as coal or coke.

The particular object of the invention is to produce a furnace having a maximum heating efficiency for a given amount of tuch-the heat being uniformly distributed throughout the entire body of air, which serves to convey it to the place or places to be heated without the overheating of any portion of said air.

To this and other ends the invention consists in certain novel features, which I will now proceed to describe and will then particularly point out in the claims.

In the accompanyingdrawings, Figure l is a vertical sectional view of a furnace embodying my invention in one form; and Fig. 2 is a plan section of the same, taken on the line a: of Fig. 1.

In the said drawings, 1 indicates the comi bustion-chamber or fire-box, which is preferably of the truncated conical form shown, being inclosed by a conical side wall 2 and a bottom 3. This combustion-chamber as thus constructed is of increasing diameter upward, its open upper end communicating directly with a heating-chamber et, located at the top of the furnace and having, preferably, a conical top 5 and a body portion 6, which extends outward some distance beyond the upper edge of the wall 2 of the combustion-chamber, thereby forming an overhang. In the lower portion of the furnace is located a second heating-chamber 7, preferably of a diameter substantially equal to or greater than the body portion 6 of the upper heating-chamber 4t, being connected therewith by a series of vertical pipes 7. The lower heating-chamber 7 comprises an annular portion 9, into which the pipes open directly, a central space lO, and a plurality of radial passages 11, extending from the annular space 9 to the central space 10. This lower heating-chamber is inclosed by an outer wail 12, preferably cylindrical in form, a top 13, which closes the upper end ot" the central space 10, and a bottom I4, provided with an opening 15, by means of which the central space IO communicates with the discharge-pipe 16, by means of which the products of combustion are conducted to the chimney orflue. Radial partitions 17, .united at their inner ends, extend from the central space 10 to the annular space 9, which latter has an inner wall 18V concentric with the outer wall l2 and having openings 19, by which the radial passages Il communicate with the annular space 9. Between the partitions 17 of the adjacent passage-ways l1 there are formed in the top and bottom plates 13 and I4 openings 20, there being thus formed through the lower heating-chamber 7 vertical passage-V ways 21, connecting the spaces above and below said heating-chamberand not in communication with the interior of said chamber. These vertical passage-ways 21 are in communication at their lower ends with an airchamber 22, which is in turn connected with the cold-air duct 23. v

24 indicates an outer casing inclosing the structure thus described and having connected to it at the top a heating-flue 25?. A diaphragm 26 may be employed to close the space between lthe heating-chamber 7 and this outer casing to prevent entrance of air between the two. The casing will be provided with a dooi` 27, while the combustion-chamber 1 is provided with a corresponding door 28, so that access may be had to the interior of said chamber. One of the vertical pipes 8 is omitted between these two doors in order to avoid obstruction between the two.

In the particular construct-ion shown, in which a furnace adapted to be heated by fuelgas is illustrated, I have shown a burner adapted for such use comprising an outer cylindrical tubular portion 29 and an inner tapering tubular portion 3Q, thespa'ce between the two being closed at the bottom, as indicated at 31, and the gas-chamber 32 thus formed between the two being of decreasing width and annular form, terminating at the top in a comparatively narrow annular jetaperture 33. The inner tapering tubular portion is open at the bottom, thus forming a central air-inlet tube 3l, by means of which air is supplied centrally to the dame. This burner extends upward through an opening iu the bottom 3 of the combustion-chamber and is surrounded within said chamber by a tubular chimney 35, preferably of cast-iron, as are also preferably the portions of the burner just described. I prefer to have the chimney extend somewhat above the top of the burner proper, and in order to render it readily removable it may rest upon the bottom of the combustion-chamber without being secured thereto, being centered or held in position laterally by means of lugs 3G ou the upper side of said bottom. Apertures 37, formed through the bottom ofthe combustionchaxnber between the chimney and burner, serve to supply air to the flame externally. The burner is connected with a supply-pipe 38, which opens laterally into the chamber 32 and which is connected with a suitable mixer 39 and provided with a controlling-valve a0.

- It will be observedvthat the burner is of less Yany suitable manner.

The furnace thus constructed operates in the following manner: The products of combustion at their highest temperature rise into the upper heating-chamber and are carried 4thence downward through the vertical pipes Sito the second heating-chamber, entering the annular space 9 therein and passing through the radial passages 1l to the central space 10, from which they are conducted by the discharge-pipe to the iiue or chimney. It will be observed that the distance from the combustion-chamber to the discharge-pipe is the same all around the structure, so that the heated products of combustion flow equally through all the pipes S and also through all ofthe annular space 9 and the radial passages 11 to the central space. The heating-surfaces of the furnace are therefore atan equal temperature throughout the corresponding portions thereof equidistant from the source of heat. The cold air enters the furnace through the vertical passages 2i of the second or lower heating-chamber and passing thence upward and outward between and around the pipes 8 are finally conducted over the highly-heated top of the upper heatingchamber 4: and thence to the heating-line. It will be observed in this connection that the cold air when it first enters the furnace is iirst warmed by the spent gases,which would otherowiug into the furnace spreads out im medi'- ately and passes between the more highly heated vertical pipes into the space between said pipes and the casing. As these pipes are necessarily at a higher temperature than the lower heating-chamber, the air already f warmed by said chamber can receive and does receive an additional increment of heat from these pipes. The air thus further heated ascends around the outer edge of the upper heating-chamber and'receives its final increment of heat from the top thereof, which is the hottest part of the heating-surface of the furnace.

It will be noted in this connection that the passages through which the products of combustion travel on their way through the furnace present successively-iucreasing areas of heated surface, these areas being increased in proportion tothe reduction of temperature of the products of combustion. It will also be observed that the incoming air is first subdivided, so as to travel over these larger areas of heated surface and be thoroughly exposed thereto, so that the heating of the airis gradual and uniform throughout the entire body thereof. In furnaces so constructed that only a portion of the air is directly exposed to the heating-surface it becomes necessary in order to obtain the desired temperature for the whole body 0f air that the portion thus exposed should be very highly heated iu order that when subsequently mixed with the cold or unheated portion the desired temperature may be obtained. This involves the raising of the healing-surface or a portion thereof to a red heat, which burns the organic dust in the air and gives rise to objectionable gases and odors. These objectionable features are avoided by the construction hereinbefore described, since the entire body of air admitted to the furnace passing through the comparatively narrow openings bounded by extensive heating-surfaces will be warmed as an entirety, and this warming as a whole will continue throughout the entire course of the air through the furnace.

It is obvious that the particular details of construction hereinbefore set forth-may be varied. For instance, the furnace may have a form other than the circular form shown. The number and size of the vertical pipes may be varied, the important point being that they shall be of such size that they will permit the reduction of the temperature of the products of combustion passing through them nearly to that of the warm air which Iiows out between them and that they shall be close enough together to cause all of the air which flows out between them to be raised nearly to the temperature of the products of combustion in the pipes. Similarly, the number of passages 1 1 and 2l may be similarly varied. Moreover, as already stated, although the particular form of construction shown is especially adapted for use with fuel-gas as a wise be Wasted, and that the air thus warmed heating medium suitable modifications in the IOO IOS

IIO

combustion-chamber, obvious to one skilled inthe art, will adapt the furnace for use with other fuel. I therefore do not wish to be understood as limiting my invention strictly to the precise details of construction hereinbe- -fore set forth, and shown in the accompanying drawings.

Having thus fully described my invention, what I claim as new, and desire to secure by Letters Patent, is-

l. In a hot-air furnace, the combination, with -a casing having a cold-air inlet at the bottom and a hot-air outlet at the top, of an inclosed heater comprising a combustionchamber, a heating-chamber at the top of the furnace in connection therewith, a second heating-chamber at the bottom of the furnace, and pipes or fines connecting said heating-chambers and having air-passages between them, said second heating-chamber being subdivided to form a plurality of passages for the products of combustion, and a corresponding plurality of passages for the incoming air, and being connected with the chimney or draft-flue, substantially as de scribed.

2. In a hot-air furnace, the combination, with a casing having a cold-air inlet at the bottom and a hot-air outletat the top, of an inclosed heater comprising a combustionchamber,a heating-chamber at the top of the furnace in connection4 therewith, a second heating-chamber at the bottom of the furnace, and pipes or flues connecting said heating-chambers and having air-passages between them, said second heating-chamber being subdivided to form a plurality of passages for the products of combustion, and a corresponding plurality of passages for the incoming air, and being connected with the chimney or draftiiue, and said heating-chainbers and pipes presenting increasing areas of heatingsurface from the combustion-chainber to the point of discharge of the products of combustion, substantially as described.

3. In a hot-air furnace, the combination, with a casing having a cold-air inlet at the bottom and a hot-airoutlet at the top, of an inclosed heater comprising a combustion-chamber and a heating-chamber in connection therewith in the upper part of the furnace, asecond heating-chamber at the bottom ot the furnace, and pipes or flues connecting said heatingchambers and having .air-passages between them, said second heatingchamber comprising an outer annular space into which said pipes or fines open, a central space closed at the top and connected at the bottom with the chimney or draft-flue, and a plurality of radial passages connecting said spaces and having formed between them airpassages for the incoming air, substantially as described.

4. In a hot-air furnace, the combination, with an inclosing casing, of a heater comprising a combustion-chamber and a heatingchamber in the upper portion of the furnace, a second heating-chamber in the lower portion of the furnace, and vertical pipes or iiues connecting said heating-chanibers, the bottom of the combustioli-chamber being above the second heatingechamber and being provided with au aperture surrounded by a chimney, and a burner extending through said aperture and comprising an annular gaschamberhavin g a similarly-shaped jet-orifice and a central air-inlet, the bottom of the combustion-chamber bein g provided with air; inlet apertures between the burner and chimney, substantially as described.

In testimony whereof I affix my signature in presence of two witnesses. l

RALPH S. THOMPSON.

Witnesses:

IRVINE MILLER, AL. H. y KUNKLE. 

